The present invention relates to a process for producing a catalyst component which can be used for the polymerization of alpha olefins. More particularly, the present invention relates to such a process which is performed in situ and does not require milling or grinding of the catalyst component.
The prior art is replete with references which disclose the improvement of the activity of alpha olefin polymerization catalysts by the addition of electron donors to the catalysts. Almost invariably, these references teach that in order to obtain high activity by the use of an electron donor, the catalyst component and electron donor must be milled or ground together to obtain intimate contact therebetween. Examples of such references are U.S. Pat. Nos. 4,120,823, 4,154,699 and 4,154,700.
There are also a number of references which teach the advantage of treating a polymerization catalyst component with an olefin to improve the activity of the catalyst. Defensive Publication T951,009 discloses the treatment of a transition metal-Lewis base catalyst component with propylene to improve its activity. The components are ground together in a ball mill before they are contacted with the propylene. U.S. Pat. No. 3,404,096 discloses a process for improving a titanium trichloride catalyst by pretreating it in an inert diluent with an olefin. There is no mention of the subsequent addition in situ of an electron donor.
It is an object of the present invention to produce an alpha olefin polymerization catalyst component in an in situ process which does not require expensive and time consuming milling or grinding to achieve intimate contact between a titanium halide and an electron donor but which achieves a level of performance which is substantially equivalent to such catalyst components which are produced with such a milling or grinding step.